The major objectives of this study are to develop and characterize a series of flagellar defective mutants of Chlamydomonas reinhardtii which will be useful in studying molecular mechanisms of flagellar motility and flagellar assembly. Flagellar proteins of mutants with defective axonemal structures will be analyzed and compared with wild-type counterparts to obtain knowledge of the molecular composition of axonemal accessory structures such as radial spokes and central pair complexes. Similar analyses will be carried out in mutants with abnormal flagellar motility. At the same time wild-type flagella will be analyzed for biochemical functions, with attempts to isolate protein kinases, dynein ATPases, accessory proteins which stabilize microtubules, etc. The protein composition of the purified enzymes will be analyzed and compared with the protein compositions of mutant axonemes to correlate biochemical functions with specific structures or specific defects of flagellar function. In selected cases, where a number of independent genes are found to affect a single structure or a specific function, attempts will be made to indentify the gene product. Flagellar function will be analyzed by stroboscopic darkfield microscopy.